The present invention relates to a filter apparatus for use in cleaning a traveling airstream in association with the operation of a textile machine, especially an open-end rotor spinning machine.
Textile machines, especially textile machines operating according to the so-called open-end spinning process, usually comprise a vacuum system which is specific, i.e., dedicated, to the machine and provides the vacuum needed for the spinning process at the multiple open-end spinning stations of the machine.
As a rule, such vacuum systems comprise a vacuum source, e.g., a suction blower, a filter chamber connected upstream of the blower, and a suction conduit running the length of the machine and emptying into the filter chamber, to which conduit the individual open-end spinning units are connected via branch lines. In addition, in many of the known open-end rotor spinning machines a suction device for cleaning the soil conveyor belts of a mechanical soil removal device arranged below the spinning units is often connected to the filter chamber or to the suction conduit.
A filter element is located inside the filter chamber, usually transversely to the flow of suction air, to filter the incoming suction air which is typically contaminated with soil particles, e.g., dirt, debris, trash, foreign matter, and fibrous waste (fiber fluff, fly and remnants), etc., whereby the filter element retains the soil particles in the filter chamber.
However, these known devices have the disadvantage that the filter element becomes heavily clogged by the soil particles after a relatively short period of operation, which results in a distinct pressure drop in the vacuum system of the textile machine. Thus, since open-end spinning machines always require a minimum vacuum for proper performance of the production process, the filter elements must be cleaned at relatively short intervals of time in the known devices.
In order to lengthen these cleaning intervals, it has already been suggested that a filter element be arranged in the filter chamber in such a manner that the filter element is self-cleaning. Such a filter element is described, e.g., in German Patent Publication DE 42 29 552 A1 wherein the vacuum system of the textile machine comprises a filter chamber with two vertically standing filter elements arranged in an L-shape. A connection for a vacuum source is positioned approximately centrally in front of one of the two filter elements whereas a suction-conduit connection arranged in the cover of the filter chamber empties slightly offset to the side into the filter chamber. The flow conditions of the incoming suction airstream which are thusly developed in such an arrangement inside the filter chamber assure that at least the filter element arranged in front of the vacuum source is cleaned of adhering soil by the motion of the soil entrained in the airstream, especially fiber fluff, fly and remnants.
The known device thus requires a sufficient amount of such fibrous waste to keep the filter element clean and accordingly is primarily designed for textile bobbin winding machines in which yarn remnants always accumulate in rather large amounts as a rule. The known device is less suitable for open-end spinning machines since fibrous waste is rather low in these textile machines in relation to the relatively fine soil particles and other trash particles which are liberated during the sliver opening step in open-end spinning and must be removed.